Direct Synthesis of 1,4‐Diols from Alkenes by Iron‐Catalyzed Aerobic Hydration and C?H Hydroxylation

Various 1,4‐diols are easily accessible from alkenes through iron‐catalyzed aerobic hydration. The reaction system consists of a user‐friendly iron phthalocyanine complex, sodium borohydride, and molecular oxygen. Furthermore, the effect of additional ligands on the iron complex was examined for a model reaction. The second hydroxy group is installed by direct C(sp³) H oxygenation, which is based on a [1,5] hydrogen shift process of a transient alkoxy radical that is formed by formal hydration of the olefin.     

A Tray‐Shaped,PdII‐Clipped Au3 Complex as a Scaffold for the Modular Assembly of [3×n] Au Ion Clusters

A tray‐shaped Pd^II₃Au^I₃ complex ( 1 ) is prepared from 3,5‐bis(3‐pyridyl)pyrazole by means of tricyclization with Au^I followed by Pd^II clipping. Tray 1 is an efficient scaffold for the modular assembly of [3×n] Au^I clusters. Treatment of 1 with the Au^I₃ tricyclic guest 2 in H₂O/CH₃CN (7:3) or H₂O results in the selective formation of a [3×2] cluster ( 1 ⋅ 2 ) or a [3×3] cluster ( 1 ⋅ 2 ⋅ 1 ), respectively. Upon subsequent addition of Ag^I ions, these complexes are converted to an unprecedented Au₃–Au₃–Ag–Au₃–Au₃ metal ion cluster.     

Structure of tecophilin,a tri-caffeoylanthocyanin from the blue petals of Tecophilaea cyanocrocus, and the mechanism of blue color development

The pigment, tecophilin, in blue flowers of Tecophilaea cyanocrocus was isolated and the structure was determined to be 3-O-(6-O-α-l-rhamnopyranosyl-β-d-glucopyranosyl)-7-O-(6-O-(4-O-(2-O-(4-O-β-d-glucopyranosyl-(E)-caffeoyl)-6-O-(4-O-β-d-glucopyranosyl-(E)-caffeoyl)-β-d-glucopyranosyl)-(E)-caffeoyl)-β-d-glucopyranosyl)delphinidin. The reproduction experiment of the same color as petals according to the results of chemical analysis and measurement of vacuolar pH of blue cells clarified that the blue color solely develops by tecophilin without interaction of metal ions nor co-pigments. ¹H NMR analysis and CD spectrum indicate the co-existence of clockwise intermolecular self-association of the delphinidin nuclei and intramolecular π–π stacking between the chromophore and caffeoyl residues to derive bathochromic shift of the absorption spectrum and stabilize the color by preventing hydration reaction.     

Enantioselective Total Synthesis of Pinnaic Acid and Halichlorine

The enantioselective total synthesis of the bioactive marine natural products pinnaic acid and halichlorine is reported in detail. Our total synthesis features the construction of the five‐membered ring and C9 and C13 stereogenic centers through a palladium‐catalyzed trimethylenemethane [3+2] cyclization; the installation of the nitrogen atom through a regioselective Beckmann rearrangement of a poorly reactive ketone; the stereoselective cyclization of the spiro ring through a four‐step, one‐pot hydrogenation–cyclization; and efficient connection of the sterically hindered lower chain through a reduced‐pressure cross olefin metathesis reaction.     

Stable Encapsulation of Acrylate Esters in Networked Molecular Capsules

Reactive acrylate esters were encapsulated in the cavity of networked molecular capsules in a single‐crystal‐to‐single‐crystal fashion. Owing to the encapsulation effect, acrylates inside the capsules do not undergo polymerization upon irradiation with UV light or heating, while the guest molecules can be quantitatively extracted by treatment with toluene.     

Structural and Electronic Influences on Rates of Tertpyridine−Amine CoIII−H Formation During Catalytic H2 Evolution in an Aqueous Environment

In this work, the differences in catalytic performance for a series of Co hydrogen evolution catalysts with different pentadentate polypyridyl ligands (L), have been rationalized by examining elementary steps of the catalytic cycle using a combination of electrochemical and transient pulse radiolysis (PR) studies in aqueous solution. Solvolysis of the [Co^II−Cl]⁺ species results in the formation of [Co^II(κ⁴-L)(OH₂)]²⁺. Further reduction produces [Co^I(κ⁴-L)(OH₂)]⁺, which undergoes a rate-limiting structural rearrangement to [Co^I(κ⁵-L)]⁺ before being protonated to form [Co^III−H]²⁺. The rate of [Co^III−H]²⁺ formation is similar for all complexes in the series. Using E_1/2 values of various Co species and pK_a values of [Co^III−H]²⁺ estimated from PR experiments, we found that while the protonation of [Co^III−H]²⁺ is unfavorable, [Co^II−H]⁺ reacts with protons to produce H₂. The catalytic activity for H₂ evolution tracks the hydricity of the [Co^II−H]⁺ intermediate.     

The Bioactive Peptide SL-13R Expands Human Umbilical Cord Blood Hematopoietic Stem and Progenitor Cells In Vitro

Hematopoietic stem and progenitor cell (HSPC) transplantation is a curative treatment of hematological disorders that has been utilized for several decades. Although umbilical cord blood (UCB) is a promising source of HSPCs, the low dose of HSPCs in these preparations limits their use, prompting need for ex vivo HSPC expansion. To establish a more efficient method to expand UCB HSPCs, we developed the bioactive peptide named SL-13R and cultured UCB HSPCs (CD34+ cells) with SL-13R in animal component-free medium containing a cytokine cocktail. Following 9 days of culture with SL-13R, the numbers of total cells, CD34+, CD38− cells, and hematopoietic stem cell (HSC)-enriched cells were significantly increased relative to control. Transplantation of cells cultured with SL-13R into immunodeficient NOD/Shi-scid/IL-2Rγ knockout mice confirmed that they possess long-term reconstitution and self-renewal ability. AHNAK, ANXA2, and PLEC all interact with SL-13R. Knockdown of these genes in UCB CD34+ cells resulted in reduced numbers of hematopoietic colonies relative to SL-13R-treated and non-knockdown controls. In summary, we have identified a novel bioactive peptide SL-13R promoting expansion of UCB CD34+ cells with long-term reconstitution and self-renewal ability, suggesting its clinical use in the future.     

Gamow-Teller strength in the exotic odd-odd nuclei 138La and 180Ta and its relevance for neutrino nucleosynthesis

The Gamow-Teller strength distributions below the particle threshold in 138La and 180Ta, deduced from high-resolution measurements of the (3He,t) reaction at 0 degrees, allow us to evaluate the role of charged-current reactions for the production of these extremely rare nuclides in neutrino-nucleosynthesis models. The analysis suggests that essentially all 138La in the Universe can be made that way. Neutrino nucleosynthesis also contributes significantly to the abundance of 180Ta but the magnitude depends on the unknown branching ratio for population of the long-lived isomer.